How to build your own AR pistol

There seems to be no end to the levels to which American tinkerers might take Eugene Stoner’s revolutionary AR-15 rifle. Arguably the greatest salient strength of this classic design is its modularity. Any law-abiding American with a credit card and an internet connection can obtain the parts to build up some fascinating AR-platform variants at home.

Building upon a stripped lower receiver bought through a federally licensed gun dealer and operating within a few basic rules, the resourceful gun enthusiast can build up a most remarkable do-it-yourself AR pistol. When mated with the revolutionary Sig Sauer SB15 Pistol Stabilizing Brace, the resulting piece of home-defense firepower is nothing short of extraordinary.

Brownell’s handguard

Brownells is a name that has joined the illustrious ranks of such luminaries as Browning, Colt and Ruger to become a staple within the American firearms industry. The company’s website is one-stop shopping for most anything that shoots—parts, ammunition, accessories, optics and more are just a click away. It couldn’t be simpler. We settled on a 7.5-inch barrel, a minimalist handguard and a standard flash suppressor. We wanted a capable firearm that was reliable and lightweight while remaining compact and maneuverable.

The Present Arms AR assembly fixtures that third hand you need to take all the pain out of an AR build.

Present Arms is a veteran-owned company that produces assembly fixtures for a bewildering array of firearms. Milled from heavy blocks of a robust and seemingly indestructible synthetic material, these fixtures are brilliantly engineered to provide that third hand you need to manage difficult disassembly, cleaning and assembly chores.

Slots are custom cut to hold parts during assembly and specific inlets make chores like swapping out charging handle latches and installing bolt hold-open switches easy and painless. Many a time I have risked both my eyesight and my sanity to install a front takedown pin in an AR lower receiver perched precariously between my knees. The fixtures from Present Arms actually make AR building a refined and civilized undertaking.

X Products’ side charging upper allows you to run the gun from the left side without shifting your grip.

Need a 50-round drum for your AR, AR .308, AR 9mm, M1A, FAL or HK91 that is skeletonized so you can watch your rounds feed while remaining reliable? X Products has it. Another interesting item was the company’s Side-Charging Upper (SCU), a drop-in proprietary component that allows easy manipulation of a standard bolt carrier assembly with the left hand.

The revolutionary Sig Sauer SB15 Pistol Stabilizing Brace is a patented accessory that fits over the buffer tube on an AR pistol and straps to a shooter’s forearm to allow better control than might otherwise be possible. Originally designed by a physical therapist for disabled veteran shooters, not only is the SB15 brilliantly revolutionary, it is also still very reasonably priced.

We also opted for an EOTech Holographic Weapon Sight (HWS) for the build. These sights have proven themselves in the military and law enforcement for years now. And finally, Winchester Ammunition, which has produced ordnance since the Indian Wars, was our choice to help test our custom AR build’s accuracy on the range once it was fully assembled.

AR Assembly

Turn the barrel nut as far as it will go and then back it off just enough to align the gas tube with the upper receiver.

With all the components in hand, it takes no more than an hour or two to construct a factory-quality firearm on your dining room table so long as you have a few basic tools. The X Products upper requires a unique bolt carrier cam pin that is included with the receiver. The Present Arms fixtures hold everything in place so pins, detents and catches that previously drove you nuts now simply drop into place. You’ll also need a dedicated wrench to tighten the barrel nut (in this case an integral component of the forearm) as well as the castellated nut that holds the buffer tube in place. However, a modest hammer, a screwdriver and a punch or two are really all that is required to do it up right on the Present Arms fixtures.

The Lower receiver fixture keeps this part in place for installing smaller pieces like the forward pivot pin.

There are some tricks. Using a .30-caliber cleaning rod to keep the detent and spring in place while installing the front pivot pin saves a lot of frustration. Wearing safety glasses also helps ensure that you don’t have to rock an eye patch at the end of the day. Tighten the barrel nut as tight as it will go, then back it off just enough so the hole for the gas tube lines up. If you run into any problems, Google can be a useful aid. But if you want to learn from the experts, visit American Gunsmithing Institute online and order up its how-to DVD called AR-15: Practical, Tactical or TACTI-COOL.

Range Time

As the SB15 Stabilizing Brace was originally designed to allow injured veterans to enjoy the shooting sports, I knew of just the guy to help us test out our remarkable new build. My buddy, Will, suffered a spinal cord injury and lost his right arm at the shoulder in a car wreck a couple years back. Will’s indefatigable faith, good humor and positive spirit are, frankly, infectious.

Present Arms donated a complete set of fixtures for Will. If these fixtures could serve as a third hand for me, perhaps they could serve as a second hand for my friend. Using the Present Arms fixtures on a bench, Will could load, fire, clear and disassemble our homebuilt AR pistol without assistance. With the SB15 and HWS in place, Will could put his rounds on target at reasonable handgun ranges. Will has always been a strong man and the combination of the pistol’s light weight, the HWS and the SB15 allowed him to run the gun like a champ.

Short-barreled ARs can be finicky, and this one hates steel-cased ammunition. However, with quality brass-cased Winchester fodder, the gun ran with 100-percent reliability. The unique combination of a homebuilt AR pistol and the extraordinary Sig brace produces a compact firearm ideal for home defense, practice and varmint hunting applications, all at a very reasonable price.

After a fun day at the range, we retreated back inside the shop to do the BATFE Form 4473 that would allow my friend Will to take his new pistol home. Limitations of the language preclude my adequately describing how pleased he was at his unexpected new addition to his home-defense arsenal.

This project really is within the grasp of anyone even reasonably competent with hand tools. The AR platform is infinitely modular, and as long as you use quality parts, the build comes together without fitting or fuss. The resulting gun is cool, compact, legal and effective while remaining a fun, low-impact Saturday afternoon building project.

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About Ballistic Advantage

Here at Ballistic Advantage we produce quality AR barrels that exceed the most enduring demands of our customers. All of our AR-15 barrels surpass the competition in accuracy, precision, and beautifully contoured aesthetics. Our engaged team of engineers and machinists continually improve designs and create new innovations to enhance performance, from our popular 16" AR barrels to all other lengths and styles we provide to produce the best functioning AR's available.